The present invention relates to orthopedic implants, and more particularly, to flexible spinal stabilization systems.
Interbody fusion device, artificial discs, interbody spacers and other devices have been inserted in a spinal disc space or engaged to a vertebral body. For example, as shown in FIG. 1, a pair of interbody fusion devices I1 and I2 are inserted into an intradiscal space between the L5 and S1 levels of the spinal column. Aorta A1 and vena cava A2 along with other tissue and vasculature also extend along the anterior aspect of the spinal column. As shown in FIG. 2, the anterior longitudinal ligament AL extends along the anterior portion of the disc space. The disc space is surrounded by annulus fibrosus or annulus fibers AF. Insertion of implants I1 and I2 into the disc space can be facilitated by the removal of all or a portion of the anterior longitudinal ligament AL and the annulus fibers AF.
In order to stabilize the spinal column, it is known to secure a rigid metal construct to each of the vertebral bodies on either side of the spinal disc space after inserting devices or performing surgical procedures in the disc space or on the vertebral bodies. For example, a rigid metal plate can be placed along the anterior aspect of the vertebrae and secured to the L5 and S1 levels after insertion of implants I1 and I2 into the disc space therebetween. In another example, a rigid rod or plate can be secured to the posterior portions of vertebrae V1 and V2 after anterior insertion of implants I1 and I2.
While rigid metal constructs provide adequate load resistance, there can be drawbacks, such as the intrusion of the construct into the adjacent tissue and vasculature, stress shielding, multiple surgeries for installation, and fatigue. What are needed are systems that do not require posterior hardware to support the spinal column or rigid anterior, antero-lateral, or lateral plates and constructs. The systems should be resistant to fatigue, stress shielding and tensile and rotational loads that are typically applied to the spinal column. The present invention is directed toward meeting these needs, among others.
The present invention is directed to spine stabilization systems that are flexible and include components that replicate, substitute and/or augment the natural fiber orientation of the anterior longitudinal ligament and annulus tissue. The components resist loading applied by extension and rotation of the spine, while the flexibility of the components does not subject them to the compressive loading of the spinal column segment to which it is secured.